This document is not restricted to specific software and hardware
versions.

The information in this document was created from the devices in a
specific lab environment. All of the devices used in this document started with
a cleared (default) configuration. If your network is live, make sure that you
understand the potential impact of any command.

This error applies to the IGX broadband trunk module (BTM) with T3 and
E3 backcards.

The bit-interleaved parity with eight bit errors (BIP-8) is an
eight-bit field in either a DS3 or E3 framing structure that can detect errors
in a frame. It uses an even parity checking method.

DS3 PLCP Frame

Bit Interleaved Parity - (B1) The BIP-8 supports path
error monitoring. The BIP-8 is calculated over the 12 x 54 octet structure that
consists of the path overhead (POH) field and the associated ATM cells (648
octets shown in Blue) of the previous PLCP frame and is inserted in the B1
octet. The nth bit of B1 provides even parity over the nth bits of the 648
octets of the 12 x 54 octet structure.

G.832/804 E3 Frame

Error Monitoring BIP- 8 (EM) One byte is allocated for
error monitoring. This function is a BIP-8 code that uses even parity. The
BIP-8 is calculated over all bits, which includes the overhead bits of the
previous frame. The computed BIP-8 is placed in the EM byte of the current
frame.

You can read further details of the framing structures in the Broadband
(ATM) Trunk Formats section of
ATM and
Broadband Trunks.

These troubleshooting activities are intrusive. Perform these steps in
a maintenance window in these circumstances:

if user traffic is affected or

if dsptrks indicates that an error
condition still persists, such as when the trunk is not in Clear-OK

Both ends of the trunk must be active when you
troubleshoot.

Issue the dsptrks command to verify that
the trunk is active. If the trunk number is not displayed in the
dsptrks screen, the trunk is not active. In order to
activate a trunk, issue the dsptrks command.

Check cabling between the local BTM backcard and the next device
upstream. Typically, the next device upstream is the local network termination
(NT).

Leave the local cabling connected to the BTM backcard, but remove
it from the NT.

Loop the cable back to the local BTM backcard with an appropriate
BNC connector. As an alternative, place the local NT into a metallic loop
toward the local customer premises equipment (CPE). In this example, the local
CPE is the local BTM. If the trunk status in dsptrks
changes to Clear-OK and dsptrkerrs no longer shows
incremental errors, the local cable and BTM card set work properly. Proceed to
Step 3.

Issue the clrtrkerrs and
dsptrkerrs commands.

Monitor dsptrkerrs for a few minutes. If the trunk status does
not change to Clear-OK or if errors continue to increment, continue with Step
2.

Check the local hardware.

Loop the cable onto the BTM backcard connector. If the trunk
status in dsptrks changes to Clear-OK and if
dsptrkerrs does not show incremental errors, the BTM
card set works properly.

Replace the cabling.

Wait at least ten seconds longer than the Red Alm Out timer
setting in cnftrkparm before you
continue.

Check cabling between the remote BTM backcard and the next device
upstream. Typically, this is the remote NT.

Leave the remote cabling connected to the BTM backcard, but
remove it from the remote NT.

Loop the cable back to the remote BTM backcard with an
appropriate BNC cable. As an alternative, place the remote NT into a metallic
loop toward the remote CPE. In this example, the remote CPE is the remote BTM.
If dsptrkerrs on the remote trunk no longer shows
incremental errors, the remote cable and BTM card set work properly.

Monitor dsptrkerrs for at least five
minutes before you proceed to Step
5.

Configure the remote NT for a Telco loop. This requires a cable
loop that uses an appropriate BNC cable. If no line-test equipment is
available, issue the dsptrkerrs command at the local
IGX and check whether incremental errors occur. If no further trunk errors are
counted, the Telco line works properly.

Remove the remote NT Telco loop and restore the trunk to service.

Issue the dsptrkerrs command at the
local IGX and check whether errors continue to increment. If BIP-8 errors
persist, proceed to Step 6.

Make sure the signal strength is sufficient and that the maximum
line length has not been exceeded. Issue the cnftrk
command to configure Line cable
length.

Ask your Telco to test the line.

If the problem persists after you perform these steps, contact the
Cisco Systems Technical Assistance Center (TAC).